Notice that trying to add a nonexistent file, we tell the user that it
doesn't exist. But trying to delete it, we extemporize about it not
being under version control — that part is OK, I expect it's coming from
checking the working copy database — but then we tell the user to use
--force as if the file actually exists on disk.

This seems like quite silly thing to do. Second of all, 'svn remove'
should really not allow removing unversioned suff from the working copy;
there's plain 'rm' for that. But first of all, if the target doesn't
exist, 'svn remove' should issue the same W155010 warning instead of
mumbling something about lost local modifications.

To summarize, I'd have expected to see something like this instead:

$ svn rm wc/foo
svn: warning: W155010: '.../wc/foo' not found
svn: E200005: '.../wc/foo' is not under version control